Module 3 - Microbial Nutrition

What is another term for a pure culture

• mono culture

• homo culture

• axenic culture

• specio culture

Answer explanation

Pure Culture (Axenic Culture)

• a culture which contains a single species of microorganism

• a population of cells arising from a single cell

Cultivation of a microbial species needs the fulfillment of their ______ and ______ needs

• physical

• chemical

• emotional

• nutritional

Answer explanation

Cultivation
• increasing the population of microorganisms by providing
their nutritional and physical requirements

Nutrients
• Extracellular substances which provide the cell with
materials for building protoplasm and for energy
generation

Select all the Micronutrients

• Zinc

• Vit B

• Proteins

• Lipids

• Calcium

Answer explanation

• Metabolic capacities of microbes differ
• Nutrient requirements also differ

• Core set of nutrients:
• Macronutrients – required in large amounts
• Micronutrients – required in minute amounts

Which component makes up a majority of the mas in an organism

• C, O, N, H, P, S

• K, Na, Mg, Cl, Fe

• H2O

• Electrons

Answer explanation

• 75% of mass is H 2 O
• 96% of dry weight is C, O, N, H, P, and S universally required by all life forms (for macromolecules proteins, lipids, polysach, lipopolysach, nucleic acids)
• 3.7% of cell’s mass is K, Na, Ca, Mg, Cl, Fe required by most (but not all) microorganisms

Autotrophs source their carbon from ______

• CO

• HCO3-

• CO2

• Macromolecules

Answer explanation

Carbon and nitrogen are present in large amounts in all cells
• Heterotrophs (organisms that require organic carbon) obtain
carbon from amino acids, fatty acids, organic acids, sugars, nitrogen bases, and other organic compounds
• Autotrophs and can synthesize organic compounds from carbon dioxide (CO2)

which statement(s) is/are false in regards to macronutrients

• All microbes can use NH3 and NO3- as a source of nitrogen

• All microbes can use amino acids and N2 as a nitrogen source

• Microbes source Phosphorous from inorganic phosphate

• Microbes source S from Sulfide only

Answer explanation

____ are inorganic cofactors

• Trace elements

• Growth factors

Answer explanation

Growth factors are organic in nature aka coenzymes

Classification for an organism that uses inorganic chemicals for an energy source and carbon dioxide as a carbon source

• Chemoautotroph / Chemolithotroph

• Chemoheterotroph / Chemoorganotroph

• Photoautotroph

• Photoheterotroph

Answer explanation

Cultural characteristics – refer to the nutrients required for growth
and the physical conditions of an environment that will favor
growth

What is NOT listed as one of the uses of a culture media

• to grow and maintain microbial cultures

• to favor the production of certain compounds

• to study the microbial action on some constituents of the medium

• to carry out staining of a microbe without damaging its internal structure

Answer explanation

• Culture media – nutrient solutions tailored to the particular
organism to be grown
• must be sterilized before use using autoclave

This media is defined by the fact that its exact nutritional composition is unknown

• defined media

• complex media

• randomized media

• non specific media

Answer explanation

• Defined media – prepared by adding precise amounts of pure inorganic or organic chemicals to distilled water
• exact composition is known

determined by trial and error

reproducible with max growth but hard to prep

• Complex media – knowledge of the exact composition of a medium is not essential
• exact nutritional composition is unknown

default media for unknown microbial cultures

no assured growth, inconsistent results prone to contamination